The present invention relates to a disk control apparatus and, more particularly, to a disk control apparatus in an information processing system (to be simply referred to as a system hereinafter) in which host computers using different coding schemes share data.
In a system in which a plurality of host computers using different coding schemes (e.g., ASCII (American Standard Code for Information Interchange) and EBCDIC (Extended Binary Coded Decimal Interchange Code)) share data, data to be processed by a given host computer must be converted into data complying with the coding scheme used in the host computer. Conventionally, such data is stored first in the main storage in the host computer, and the host computer then performs code conversion processing by software or hardware means.
Japanese Patent Laid-Open Nos. 61-253673 (reference 1) and 5-67023 (reference 2) are the prior arts associated with the present invention. The xe2x80x9cCode Converting System for Magnetic Disk Devicexe2x80x9d disclosed in reference 1 aims at a magnetic disk device that converts stored data into a predetermined code, writes the code on a magnetic disk upon modulation, converts the code read out from the magnetic disk into the original data, and outputs it. This system is not designed for conversion of the coding scheme of data to be processed by a host computer as in the present invention.
According to the xe2x80x9cCode Conversion Processing System for Magnetic Disk Writingxe2x80x9d, the time required for code conversion is shortened by simultaneously executing disk seek processing and code conversion processing. Similar to the xe2x80x9cCode Converting System for Magnetic Disk Devicexe2x80x9d disclosed in reference 1, this system is not designed for conversion of the coding scheme of data to be processed by a host computer.
In the prior arts described above, when code conversion processing for data is to be performed by a host computer using a software means in accordance with a program, the processing efficiency of the host computer decreases.
In addition, when code conversion processing for data is to be performed by conversion circuits prepared as hardware means in a host computer, such conversion circuits must be prepared for the respective channels in the host computer, resulting in an increase in system size.
It is an object of the present invention to provide a disk control apparatus that obviates the necessity of code conversion processing for data in a host computer.
In order to achieve the above object, according to the present invention, there is provided a disk control apparatus comprising control means for analyzing read/write commands transmitted from a plurality of host computers using different coding schemes, and recognizing a code conversion mode which indicates execution/inexecution of code conversion and a code conversion direction, and code conversion means for performing code conversion for data to be read/write from/in a plurality of disk storage units using different coding schemes.